The disclosed invention is generally directed to ink jet printing, and more particularly to a technique for ink jet printing that reduces the amount of ink that is deposited off a print medium in edge to edge printing.
An ink jet printer forms a printed image by printing a pattern of individual dots at particular locations of an array defined for the printing medium. The locations are conveniently visualized as being small dots in a rectilinear array. The locations are sometimes called xe2x80x9cdot locations,xe2x80x9d xe2x80x9cdot positions,xe2x80x9d or xe2x80x9cpixelsxe2x80x9d. Thus, the printing operation can be viewed as the filling of a pattern of dot locations with dots of ink.
Ink jet printers print dots by ejecting very small drops of ink onto the print medium, and typically include a movable carriage that supports one or more printheads each having ink ejecting nozzles. The carriage traverses over the surface of the print medium, and the nozzles are controlled to eject drops of ink at appropriate times pursuant to command of a microcomputer or other controller, wherein the timing of the application of the ink drops is intended to correspond to the pattern of pixels of the image being printed.
For a variety of reasons including avoidance of drop to drop ink interaction, and compensation for print mechanism mechanical errors and printhead errors, ink jet printing commonly employs multiple-pass print modes wherein the pixels of a row are printed in multiple passes or scans of the ink jet printheads. In other words, as to a row of pixels, the printed pattern of a given color is filled pursuant to multiple passes of the printheads wherein only a portion of the printed pattern is filled in each pass. Typically, the print medium is advanced between passes of the printheads, for example by a fraction of a swath height which is the extent along the media advance axis that a printhead can print in a single pass. For example, in a four pass print mode, a pixel row is printed in four passes and the print medium is advanced one-fourth of a swath between passes.
A consideration with multiple pass print modes is the accumulation of print media positioning errors whereby the dots printed on one pass are not precisely aligned along the media with the dots printed on another pass. When edge to edge or xe2x80x9cfull bleedxe2x80x9d printing is being performed, this can lead to excessive amounts of ink being deposited off the leading edge and trailing edge of the print media onto the media handling mechanism of the printer. Such off-media ink deposition causes unwanted marking of the back side of print media subsequently printed, which is deleterious to double sided printing. Also, the off-axis deposition of ink could cause the media advance mechanism to malfunction.
There is accordingly a need to reduce off-media printing in ink jet printers.
The disclosed invention is directed to a method of ink jet printing wherein at least one pixel row adjacent an edge of a print medium is printed using a print mode that employs fewer passes than a print mode utilized to print pixel rows that are further from such edge.